Narrative:

While on bowie 1 arrival to dfw, approach had cleared us to maintain 6000 ft. Crew observed TCASII traffic at 2 O'clock, 5 mi, 500 ft above, and descending. Dfw approach called the traffic and crew acknowledged visual contact. TCASII gave a TA followed by an RA 'descend, descend' with a 1500 FPM descent rate command. Crew initiated descent as dfw approach cleared flight to descend to 5000 ft MSL. Cause of problem: dfw approach requires arriving turboprop air carrier aircraft to be at 6000-7000 ft over 70 NM from hub. This causes aircraft to enter class B airspace from the side instead of the top. It puts the air carrier aircraft on a perpendicular course to GA aircraft as the GA aircraft circumnav the class B. This near midair collision occurred 5 NM outside of class B. Callback conversation with reporter revealed the following information: reporter adds that the VFR traffic circumnaving the airspace above 3000 ft AGL may or may not be flying at appropriate altitudes for the direction of flight. If these aircraft are changing altitudes to adjust for the direction of flight, then they may be descending or climbing through a 1000 ft altitude at just about the time that an air carrier aircraft is inbound from one of the dfw 'corner posts' (in this incident, bowie VOR).

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Original NASA ASRS Text

Title: AN AT72 COMMUTER FO RPTS RESPONDING TO A TCASII RA WHILE 5 NM NW OF THE DFW CLASS B AIRSPACE. RPTR COMPLAINS ABOUT THE NEW ATC PROCS REQUIRING TURBOPROPS TO DSND TO BTWN 6000 FT AND 7000 FT, 70 NM OUT FROM DFW.

Narrative: WHILE ON BOWIE 1 ARR TO DFW, APCH HAD CLRED US TO MAINTAIN 6000 FT. CREW OBSERVED TCASII TFC AT 2 O'CLOCK, 5 MI, 500 FT ABOVE, AND DSNDING. DFW APCH CALLED THE TFC AND CREW ACKNOWLEDGED VISUAL CONTACT. TCASII GAVE A TA FOLLOWED BY AN RA 'DSND, DSND' WITH A 1500 FPM DSCNT RATE COMMAND. CREW INITIATED DSCNT AS DFW APCH CLRED FLT TO DSND TO 5000 FT MSL. CAUSE OF PROB: DFW APCH REQUIRES ARRIVING TURBOPROP ACR ACFT TO BE AT 6000-7000 FT OVER 70 NM FROM HUB. THIS CAUSES ACFT TO ENTER CLASS B AIRSPACE FROM THE SIDE INSTEAD OF THE TOP. IT PUTS THE ACR ACFT ON A PERPENDICULAR COURSE TO GA ACFT AS THE GA ACFT CIRCUMNAV THE CLASS B. THIS NMAC OCCURRED 5 NM OUTSIDE OF CLASS B. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR ADDS THAT THE VFR TFC CIRCUMNAVING THE AIRSPACE ABOVE 3000 FT AGL MAY OR MAY NOT BE FLYING AT APPROPRIATE ALTS FOR THE DIRECTION OF FLT. IF THESE ACFT ARE CHANGING ALTS TO ADJUST FOR THE DIRECTION OF FLT, THEN THEY MAY BE DSNDING OR CLBING THROUGH A 1000 FT ALT AT JUST ABOUT THE TIME THAT AN ACR ACFT IS INBOUND FROM ONE OF THE DFW 'CORNER POSTS' (IN THIS INCIDENT, BOWIE VOR).

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.